Compressor



Oct. 28, 1952 M. k. A. CHABAY 2,615,618

COMPRESSOR Filed July 51, 1947 v s Sheets- Sheet 1 "and Kin; Nmma Qh 6Pa Oct. 28, 1952 M. R. A. CHABAY 2,615,618

COMPRESSOR Filed July 51, 1947 3 Sheets-Sheet 2 Mar e e,\ Kin N'mmtkQMABA Oct. 28, 1952 M. R. A. CHABAY 2,615,618

COMPRESSOR Filed July 31, 1947 3 Sheets-Sheet 3 Mad!) Kim: M- mandekablmvzuro \r T w s 2 2 5 A 3 w I 9 m .3 23947670. 7 o r w flfl 3 Illll V4wig.. G E

Patented Oct. 28 1952 f umreo STATES PATENT joFFIce COM SO MarcelRenArinand. Chabay} Paris, France Application'July s1; 1947,'seria1'No.765,187

InFrance April 1, 1941 The present invention relates to improvements incompressors provided with pistons. Incompressors of known types therotation speed of the crank-shaft upon which'are pivoted theconnectingrod-s pertaining to the piston or pistons is limited; this fact involvesimmediately a corresponding limit-ati-onof the output of the compressordue to the fact that it becomes diificult to fill the cylinder and toevacuate th gaseous fluid contained in the cylinders. I

In nearly all of the known compressors the in let of the gaseous fluidinto the respective -cylin-- der is effected by means of a'p'ortsituated in the cylinder or on the cylinder head and controlled byavalve. The same; arrangement is also em;

ployed for the outlet. At high speeds thethrot tling of the gaseousfluid produced by these valves involves important losses/of charge thisbeing prejudiciable for the obtainment of a' good output; As regards thefilling of the cylinders, ex'

' end'cylinder I comprises a cover 4 provided with periments executed byapplicant have shown that in the neighbourhood of the cylinder jbottomsfexists a depression space during the filling stroke which gives evidenceof a bad filling of the cylinders. s

"In order to avoid this very serious drawback, the present inventionprovides ports in thewalls of the cylinder; these ports communicatingwith thesource of fluidan-d being uncovered when the piston arrivestowards the end of its inlet stroke. f

According to another feature ofthe invention, another port is providedtogether with a control valve in the closed end or in the head of thecylinder. According to another feature of the invention, the outletports are provided in the cylinder heads or covers and are controlled byautomatic balanced valves adapted for instantaneous opening andoperating as soon as the pressure in the cylinder exceeds a certainvalue.

Qther features will appear from the following specification withreference to the annexed drawin'gs. In these drawings:

pressor provided with pistons comprising the im provements according tothe invention;

' Fig. 2 isa development of the cylinder show-f ports and of t 45 Fig. 1is an axial section of a cylinder of a com-.

inlet conduits 5 and outlet conduits 6, said cover being secured bymeans of studs or the like On this cover 4 is secured in atight way andby means of studs 1 for instance apiece 8 serving, as'a guide for theinletva'lves 9 and theoutlet valves I0 of the cylinder. Y I

'Inlet valve 9 is held' by spring ll onits 'se'at I2 which might be madein one with piece-'8. Outlet valve Iflrests on'its seat I3 pertainin to7 cover .4. In the embodiment represented in Figures 1 to 3, this inletvalve comprises means permitting of controlling its'opening either by acam or by an overturn device M (as represented) pivoted on a shaft I5and controlled by a pushing rod I6 which latter is subjected on itsother end to the action of a cam-which has not been shown.

I According to a feature of the invention, the" outlet valve I0 isadapted for an instantaneous and automatic opening. As in Fig. 1, thetail portion ll of this valve is guided in a'suitable hole provided inpiece 8; s Y I :According to a very important feature of the invention,this outlet valve is moreover locked in its closing position duringthewhole conipressive stroke of piston l8 sliding in cylinder: I orduring a part of this stroke. In an embodiment which for the time beingseems to be advantageous this locking is efiectedwith the aid ofresilient means; Tail portion ll of outlet valve [0 comprises an axialclosed bore 2| in: which is located a small piston 20 subjected to theupward action of a spring l9 located in the bore 2|. At its upper endpiston-20 meets a hole 22 provided in piece 8 and may get in contactwith a pusher 23 which is adjustable and providedat one end of aturnover device 24 pivoted on a shaft 25 mounted on a'suitableprotrusion of piece 8. The other end of turnover device 24 is controlledeither directly by a cam or by a pusher which in turn is controlled by acam.

M This cam is moved in synchronism with the crankshaft and has asuitable shape in order that the resilient locking of valve l0 mighttake place during the whole stroke of compression or a part thereof.

The valve [0 is subjected on one of its faces to the pressure prevailingin cylinder l. Its opposite face is subjected to the pressure prevailingin the outlet conduit 6, which is always less important than thepressure prevailing inside the cylinder 1, whereas the stem I1 issubjected to the pressure resulting from the action of spring i9 and arm24. The dimensions of the valve faces and the diameter of the stem I1are given such values that when the pressure inside cylinder l exceeds acertain predetermined value, the opposite pressures (in 6 and I) becomeinsufficient so that the opening of valve I0 is executed automatically.

Piston 20 also comprises a shoulder 26 which comes in contact with theedge of bore 22 of piece 8 when the valve 10 is opened. This contactpushes piston 20 downwards against the action of spring [9, thus ensurina resilient braking of valve I0 at the end of its opening stroke.

According to the invention and as shown in Figs. 1 and 2, the innerlateral wall of cylinder 1 comprises ports 21 located on the peripheryof this cylinder. In the represented embodiment, the number of holes orports 21 is eight. These ports assume such a position, that theywill beuncovered by piston l8 when this latter arrives at its lowermostposition. These ports 21 are connected with conduits 28 provided in thewall of cylinder l with the inlet piping 29, or suction piping.According to the invention and in order to facilitate the arrangement ofconduits 28 in the wall of cylinder I, these latter conduits 28 have a.section corresponding to the section of ports 21 and are preferablydistributed on both sides of a middle horizontal plane. passing throughthe axis of said ports as shown in Figure 2.

According to another important feature of the invention, the section ofthese ports is chosen in such way that the gaseous fluid might easilyenter the cylinder. Moreover, the shape of these ports is such thattheir height is relatively small so as to avoid the backfiow of the gasduring the liftingmotion of the piston. Numerous experiments executed byapplicant have shown that due to this logical choice of thecross-section and of the shape of these ports, a real overfeeding of thecylinder is obtained, because of the transformation of the kineticenergy of the gas into pressure energy. This overfeeding is obtained forinstance by rectangular ports the section of which is suflicient toavoid as far as possible losses of charge. The edges of these ports arerounded and their height which is relatively small with respect to theirlength depends upon the linear speed of the piston and upon the diameterthereof. It is also possible to use trape- Zoidal, triangular,semicircular or even circular ports disposed, as regards the three firstshapes, in order that the width thereof should decrease along thecompressive stroke.

Due to theuse of ports having such a shape and arrangement it becomespossible to obtain a perfect filling of the cylinders whatever be thelinear speeds of the piston. This result, as

numerous experiments have shown it, cannotbe obtained with the knowncompressors. Thus applicant could observe durin these experiments thatthe filling coeflicient of the cylinder increases together with thespeed of the piston due to the transformation of the kinetic energy-intopressure energy, at the moment when the gases pass through the portsprovided in the cylinder walls.

Preferably the ports are slightly convergent so as to form a kind ofVenturi tubes at the spot where they open into the cylinder, this factpermitting on the one hand of improving the said transformation of theenergy (from kinetic into pressure) inside the cylinder, and on theother hand of having a coeflicient of contraction of the gaseous veinnearly equal to The ports open in the cylinder through an orifice havinga sharp edge. This fact combined with the above mentioned constructionalfeatures of the ports, permit of avoiding any backflow of the gas durinthe upward movement of the piston.

In order to obtain a most regular flow of fluid without any whirl whenarriving into ports 21, pipings 28 provided in cylinder I have aconstant shape, their area varying progressively from the pipe 29 up toports 21 in order to correspond to the cross-section of these latter.

The operation of the compressor according to the invention is asfollows. At the beginning of the suction stroke of the piston [8, theoutlet valve [0 is closed and looked as shown hereabove. The inlet valve9 opens under the action of turnover device [4 either at the beginningof the suction period, or with a certain delay, if desired. The gaseousfluid enters then into cylinder I by the upper end thereof. When thepistonv arrives to its lowermost position, it opens ports 21 and the gasthen flows into the cylinder 1 through those ports ensuring thusaperfect filling of the cylinder. In fact, the upper space of thiscylinder is filled by the gas arriving through valve 9 and the lowerportion thereof is filled by the gas arriving by the ports 21.

At the beginning of the compressive stroke of piston [8, or even beforethis moment valve 9 is closed under the action of spring H piston l8closes in turn ports 21 and the fluid contained in cylinder I iscompressed up to the moment when outlet valve Ill, which has beenunlockedin due course, as indicated above, is opened and permits thecompressed fluid of passing into pipe 6.

It is possible to provide on each cylinder of the compressor anautomatic device of any known type permitting the operation withoutpressure. Such well known devices will not be described in the presentspecification.

In the modification represented in Figure 4 the inlet ports and theoutlet valve with its automatic locking control are identical with thoseindicated hereabove and will of course not be described once again. Thesame numeral references indicate the same parts of the apparatusrepresented in Figs. 1 to 3. However, in this embodiment spring 2! hasbeen replaced by resilient (rubber for instance) rings 30. Moreover, theoutlet valve In has been shown here in axial arrangement with respectto. cylinder 1.

According to the invention and as shown in Fi 4, the inlet valve is ofthe type provided with means for an automatic opening and consists of aflap 3| having an annular shape guided ina. hole 32 provided in acircular plate 33. This latter plate is secured on cover 4 by bolts 38and ismoreover maintained at its periphery between the upper part ofsleeve 3 and cover 4. This circular plate 33 comprises at its peripheryholes 34 abutting on the one hand, into boring 32 adjacent flap 3| and,on the other hand, into a convergent annular chamber 35 provided oncover 4 and communicating with the inlet piping 5, also provided on thiscover, by means of a pipe having a progressively decreasing section, theprogression depending upon the cross-section of borings 34.

The operation of this compressor is identical to that described withreference to the embodiment represented in Figures 1 to 3, except that vthe automatic closing and opening of the inlet valve are controlled bythe depression and the pressure prevailing in cylinder I.

In the embodiment shown in Figure 5 the inlet valve is analogous to theone described with reference to Fig. 4; however outlet valve It beingadapted for automatic opening and closing (as in the preceding examples)does not comprise anymore any locking of the controlled type. In orderto damp the shock which occurs when this valve Ill is suddenly andinstantaneously opened, the tail portion [1 thereof slides in a hollowportion 36 provided in piece 8 secured on cover 4, this portion 36 beingconnected with the atmosphere by orifice 31 having a given cross-sectionin order that the whole arrangement should act as a dash-pot. A spring39 is also provided to cooperate for the closing of the valve Hi.

It is obvious that the invention is not limited to the embodimentsherein represented and described, and that it covers all the cases whereuse is made of any one of the features above indicated. Thus forinstance, the outlet valve or valves may be of the type wherein theopening and closing thereof is controlled by any suitable means in orderthat these valves should operate under a predetermined pressure.Moreover, the present invention also covers the use of the abovementioned ports 21 (whatever be their cross-section and arrangement) incompressors of any known or unknown types, for instance in singleflowcompressors, in double-flow compressors and the like.

It is also possible, without departing from the scope of this inventionto use only these ports without any other inlet means with a controlledvalve, this being chiefly the case of compressors having a small strokeor a very high pressure.

The present invention also contemplates compressors of any known typeincorporating one of the above indicated features.

Having now described and ascertained my invention, what I claim as newand desire to secure by Letters Patent is:

1. A compressor comprising at least one cylinder, a piston reciprocatingtherein and adapted to compress a fluid during a single stroke, saidpiston comprising a head portion creating said compression and an underportion subjected to no compression at all, inlet and outlet valve meansin said cylinder, means for the positive control of said inlet valvemeans, lateral aper- 6 tures in said cylinder, said apertures being ofan elongated shape, their height being substantially smaller than theirlength, said apertures being located in proximity of the lower deadcenter of the piston and being adapted to be uncovered thereby when saidlatter arrives at said dead center, tubular inlet means for said fluidprovided with two equivalent branches adapted to connect directly saidinlet means, first, said apertures, and secondly, with said inlet valvemeans, the said branches being adapted to provide upon the closure ofthe inlet valve means a continuous flow of the fluid into said cylinderthrough said apertures, thereby transforming the kinetic energy of saidfluid into pressure energ said outlet valve means comprising a stem anda main body, the two opposite faces of which are subjected,respectively, to the pressure prevailing in the cylinder and to thecombined pressure exerted on the opposite face of said body by theoutlet back pressure fluid and on the stem by the inlet pressure, saidpressures on the area of i said body and stem being adapted to create abalanced condition of said valve, further means provided for holdingsaid outlet valve means in the closed position at least during thesuction stroke of the piston, resilient means disposed in contact withsaid stem to yieldingly urge said outlet valve into closed position, apiston-like member supported over said resilient means and a controldevice acting on said piston.

2. A compressor according to claim 1, in which the inlet valve isannular and surrounds the outlet valve, and in which said stem comprisesa sleeve with said resilient means within the sleeve.

3. A compressor according to claim 1, in which the resilient means isnon-metallic.

MARCEL ARMAND CHABAY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 304,836 MacDonald Sept. 9, 1884421,414 MacDonald Feb. 18, 1890 583,075 Niebling May 25, 1897 635,531Edwards Oct. 24, 1899 711,939 Coombs Oct. 28, 1902 1,668,664 Van HornMay 8, 1928 1,891,083 Dodge Dec. 13, 1932 1,938,472 Wainright Dec. 5,1933 2,113,691 Heller Apr. 12, 1938 FOREIGN PATENTS Number Country Date76,256 Austria Apr. 25, 1919 596,925 Germany 1934

